Detachable securement of an accessory device to a handheld computer

ABSTRACT

Embodiments of this invention provide for coupling an accessory device to a back face of a handheld computer while electrically connecting to the handheld computer through a communications or output port. In one embodiment, the accessory device &#34;piggy-backs&#34; on the handheld computer so that the accessory device and handheld computer form a portable combination. An insertion coupling may be used to detachably secure the accessory device with the handheld computer. The insertion coupling used with embodiments of the invention is preferably a snap-in coupling having one or more biased members. The biased members may be contracted to engage an aperture on a back face of the handled computer. When released, the biased members secure the accessory device to the handheld computer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to a handheld computing device. Morespecifically, embodiments of this invention provide for detachablysecuring an accessory device to a handheld computer using an insertioncoupling.

2. Description of the Related Art

A principal feature of handheld computers is portability. To this end,functions and features of handheld computers are sometimes sacrificed tomaintain the handheld computer in a small, compacted state. Additionalfeatures and functions of the handheld computer may be added by linkingthe handheld computer to an accessory device. Examples of such accessorydevices includes modem devices and communication cradles.

Previous accessory devices have generally been immobile, so that thehandheld computer had to use the accessory device as a docking port.However, the widespread use of computers and computer networks hasresulted in a need for accessory devices that are portable. Therefore,there is an increasing need for enabling accessory devices to securelycouple with a handheld computer without hindering the portability of thehandheld computer.

Other previous accessory devices that have been designed to be portablewith the handheld computer have relied on coupling mechanism that allowsthe accessory device to couple with the handheld computer by firstplacing the handheld computer on the accessory device, and thenmaneuvering portions of the accessory device around the handheldcomputer to secure it with the accessory devices. Such couplingmechanisms are overly complicated, requiring the user to perform toomany steps and maneuvers to secure the accessory device with thehandheld computer. Requiring additional steps to secure the accessorydevice with the handheld computer leaves the handheld computer prone tobeing dropped prior to it being secured. This is especially problematicconsidering that these accessory devices require a free hand from theuser for the sole purpose of manipulating portions of the accessorydevice to secure the handheld computer.

SUMMARY OF THE INVENTION

Embodiments of this invention provide for coupling an accessory deviceto a back face of a handheld computer while electrically connecting tothe handheld computer through a communications or output port. In oneembodiment, the accessory device "piggy-backs" on the handheld computerso that the accessory device and handheld computer form a portablecombination. An insertion coupling may be used to detachably secure theaccessory device with the handheld computer. The insertion coupling usedwith embodiments of the invention is preferably a snap-in couplinghaving one or more biased members. The biased members may be contractedto engage an aperture on a back face of the handheld computer. Whenreleased, the biased members secure the accessory device to the handheldcomputer.

In an embodiment, the accessory device incorporates an insertioncoupling and has dimensions that complement the handheld computer. Theaccessory device may then be readily secured to the handheld computer sothat the combination of the two devices is portable and easy to handle.Embodiments of the invention may be incorporated with, for example,modem devices which can add communication abilities to the handheldcomputer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a handheld computer coupled to an accessory deviceunder an embodiment of this invention.

FIG. 1B shows a side view of FIG. 1A.

FIG. 2A shows a back side of a handheld computer under an embodiment ofthis invention.

FIG. 2B shows a front side of an accessory device under an embodiment ofthis invention.

FIG. 3 is exploded isometric view of a mechanical coupling incorporatedinto an accessory device under an embodiment of this invention.

FIG. 4 is a top view of a retainer used with an embodiment of theinvention.

FIG. 5A is a side view of FIG. 4 showing the insertion coupling in adisengaged position, under an embodiment of the invention.

FIG. 5B is a side view of FIG. 4 showing the insertion coupling retainedin an engaged position, under an embodiment of the invention.

FIG. 6A is a side view of a latch mechanism in an engaged position underan embodiment of the invention.

FIG. 6B is a side view of the latch mechanism of FIG. 6A in a disengagedposition, under an embodiment of the invention.

DETAILED DESCRIPTION

Embodiments of this invention provide for an insertion coupling thatallows an accessory device to be coupled to and secured with a handheldcomputer. An embodiment of this invention couples an accessory device toa back face of a handheld computer while a coupling of the accessorydevice connects to a communications or output port of the handheldcomputer. The accessory device is aligned in a "piggy-back" positionwith the handheld computer so that the accessory device and handheldcomputer form a portable combination that enables the accessory deviceto be carried with the handheld computer using a single hand. Theaccessory device is coupled to the handheld computer by use of amechanical coupling that inserts into the back face of the handheldcomputer. The mechanical coupling may further provide a tactile responsethat signals a secure engagement between the handheld computer and theaccessory device. Preferably, the accessory device has lateral andlongitudinal dimensions that complements the handheld computer'sdimensions so that the combination of the two devices is easy to hold.The accessory device may include, for example, a modem accessory deviceswhich can add communication abilities to the handheld computer. Forpurpose of this disclosure, a handheld computer is a combination of aprocessor and memory, having a portable energy source, and being housedin a manner to be carried with one hand.

FIG. 1A illustrates a handheld computer 100 that is detachably coupledto an accessory device 110 under an embodiment of this invention. Thehandheld computer 100 may include palm style computers such as a Palmpilot™, Palm III™, or Palm V™, or Palm VII™ organizers, manufactured bythe 3Com Corporation. Other embodiments of the invention can includeWindows CE™ handheld computers, or other handheld computers and personaldigital assistants.

Preferably, the handheld computer 100 has interactive hardware andsoftware that perform functions such as maintaining calendars and phonelists. The handheld computer 100 shown in FIG. 1 includes a plurality ofinput functions keys 117 and a display 113 having graphic user interfacefeatures. The display 113 may be provided with an interface that allowsthe user to select and alter displayed content using a pointer such as astylus. In an embodiment, the display 113 also includes a Graffiti™writing section 118 for tracing alphanumeric characters as input. Aplurality of input buttons 119 for performing automated orpre-programmed functions may be provided on a portion of the display113.

The accessory device 110 may be one of several types of accessories,such as a modem device for serial and/or wireless data communications, aUniversal Serial Bus (USB) device, or a communication cradle having anextended housing. The accessory device 110 may include one or more portsfor parallel and/or serial data transfer with other computers or datanetworks. The handheld computer 100 may use the accessory device 110 forthe purpose of downloading and uploading software, and for synchronizingdata on the handheld computer 100 with a personal computer (not shown,but may be included or used with some embodiments of the invention). Theaccessory device 110 couples to the handheld computer 100 through anelectrical connector (see FIG. 2A) located at a bottom portion of itsfront face. A button 155 on the accessory device 110 may effectuate anelectrical connection between the accessory device 110 and the handheldcomputer 100 when the two are connected.

In an embodiment, the accessory device has a housing that is shapedaccording to the dimensions and contours of the handheld computer 100.The accessory device 110 may be referenced with respect to a pair ofopposing lateral sides 115, 115, a top edge 112, and a bottom edge 114.Similarly, the handheld computer 100 may be referenced with respect toopposing lateral edges 105, 105 a top edge 102, and a bottom edge 104. Awidth of the accessory device 110 defined as a distance between lateralsides 115, 115 is preferably fractionally less than a correspondingwidth of the handled computer 100 between lateral edges 105, 105. Thetop edge 112 of the accessory device 110 is also only a fraction lessthan a corresponding top edge 102 of the handheld computer 100. A bottomedge 114 of the accessory device 110 extends beyond a bottom edge 104 ofthe handheld computer 100 and forms a ledge 116. Preferably, the ledge116 is contoured to match a thickness profile of the handheld computer100.

FIG. 1B illustrates the accessory device 110 of an embodiment contouredand dimensioned to detachably retain the handheld computer 100. Theaccessory device 110 includes a front face 262 (shown in FIG. 2B) thatextends a majority portion of a back face 212 (shown in FIG. 2A) of thehandheld computer 100. The ledge 116 includes a concaved surface 106 tomatch the thickness profile of the handheld computer 100. Whenmechanically coupled, the handheld computer 100 abuts and contacts thefront face 262 of the accessory device 110, with the electricalconnector of the accessory device 110 in contact with a connector in anoutput port 210 (FIG. 2A) of the handheld computer 100.

FIG. 2A illustrates the back face 212 of the handheld computer for usewith an embodiment of this invention. An output port 210 is positionedadjacent to the bottom edge 104 of the handheld computer 100. The outputport 210 includes an insulative body 216 that houses a plurality ofelectrical contacts 211. An aperture 220 is adapted to receive aninsertion coupling 250 (see FIGS. 2B-6B) extending from the accessorydevice 110. In an embodiment, the aperture 220 is rectangular to matchthe shape of a spring-biased first member 375 (FIG. 3) extending fromthe coupling. A recess portion 225 on the back face 212 provides headroom to receive the insertion coupling 250 into the aperture 220. A pairof alignment protrusions 218 are aligned on the back face 212 to engagealignment surfaces 228 (see FIG. 2B) of the accessory device 110. Thealignment protrusions 218 ensure that the output port 210 connects withan electrical connector of the accessory device 110 (discussed with FIG.2).

FIG. 2B illustrates the front face 262 of the accessory device 110 underan embodiment of the invention. The insertion coupling 250 extends fromthe front face 262. As will be further described, the insertion coupling250 is adapted to engage the aperture 220 on the back face 212 of thehandheld computer 100. Preferably, the distance between the opposinglateral sides 115, 115 of the accessory device 110 is slightly less thanor equal to the corresponding width of the handheld computer 100. In anembodiment, the width of the accessory device 110 is approximately 90%of the width of the handheld computer 100. For example, a handheldcomputer 100 such as the Palm V™ measures approximately 3.0" between itslateral edges 105, and a preferred accessory device 110 measures 1.75".Similarly, the top edge 102 of the handheld computer 100 issubstantially in alignment with the top edge 112 of the accessory device110. The bottom edge 114 of the accessory device 110 extends beyond thebottom edge 104 of the handheld computer 100 and shapes into the ledge116 that cradles and supports the handheld computer 100 from the bottom.When coupled, the handheld computer 100 and the accessory device 100 maybe grasped with a single hand and carried together as a single unit. Thefront face 262 is contoured on the perimeter to match the shape of thehandheld computer 100, so that the two devices better form a unit whencoupled.

A bottom opening 258 on the front face 262 accesses an electricalconnector (not shown) of the accessory device 110 to the handheldcomputer 100. The bottom opening 258 is preferably positioned adjacentto the ledge 116 so that the electrical connector can be angled parallelor acutely with respect to the front face 262. This position allows theelectrical connector to couple to the output port 210 on the bottom edge114 of the handheld computer 100. In alternative embodiments, theelectrical connector may extend outward from the front face 262, or thebottom opening 258 may be positioned elsewhere on the device to accessthe electrical connector with other communication ports such as IRports, PCMCIA slots, and RJ connectors. The alignment surfaces 228 onthe front face 262 are aligned and adapted to receive the alignmentprotrusions 218 of the accessory device 110.

FIG. 3 details an insertion coupling 250 of an embodiment of thisinvention incorporated into an accessory device 110. The accessorydevice 110 includes a housing formed from a front panel 310 joined witha back panel 320. The back panel 320 is adapted to align with aperipheral rim 322 of the front panel 310, and a plurality of connectorholes 318, 319 are used to receive fasteners which secure the front andback panels 310 and 320 together.

A length of the accessory device 110 is defined by a distance betweenthe top and bottom edge 112 and 114. The periphery of the accessorydevice 110 is contoured to match the shape of the handheld computer 100.The front and back panels 310 and 320 each include a respective flairportion 340, 342 near the bottom edge 104. The resulting contour of theperiphery of the accessory device 10 matches the shape of a Palm III™ orPalm V™ organizers.

The front panel 310 includes an exterior side that forms the front face262 (shown in FIG. 2B) of the accessory device 110. Similarly, the backpanel 320 includes a back face 352 for the accessory device 110. Thebottom portion of the front panel 310 includes the bottom opening 258for accessing an electrical connector (not shown) of the accessorydevice 110 with an output port 210 (shown in FIG. 2A) of the handheldcomputer 100.

The insertion coupling 250 engages and is accessible through an opening386 in a front portion of the front panel 310. The insertion coupling250 includes a base 385 that secures to the interior of the front panel310. The base 385 is preferably flat with respect to the front panel310. A pair of apertures 381 and 383 of the base 385 are aligned overcorresponding fastener holes 321 and 323 on the interior of the frontpanel 310. The fastener holes 321 and 323 receive fasteners 382 and 384that secure the insertion coupling 250 to the front panel 310.

The insertion coupling 250 includes a first member 375 that moveablycouples to the base 385 and extends in an orthogonal direction from thebase 385 beyond the front face 354. A second member 380 is fixed withrespect to the base 385 and extends in the orthogonal direction adjacentto the first member 375 so as to be staggered with respect to the firstmember 375. The first member 375 is slideably coupled to the base 385 tobe moveable in a lateral direction. The first member 375 couples to thebase 385 by engaging a torsion spring 366 so that the torsion stringbiases the first member 375 in the lateral direction with respect to thebase 385. In this way, first member 375 is moveable into a contractedposition in which the torsion spring 366 is biased and the first andsecond members 375 and 380 are laterally aligned with one another. Inthis position, the lateral length of the combination of the first andsecond members 375 and 380 is a minimum. When released into an extendedposition, the first member 375 extends laterally away from the secondmember 380.

The first member 375 includes a tail portion 367 which extends to theback face 352 of the accessory device 110. The first member 375 may bemoved between the extended and contracted position by moving either thefirst member 375 or its tail portion 367.

The insertion coupling 250 further includes a retainer 360 that insertsthrough the opening 386. The retainer 360 engages the front face 262while either retaining or exposing the first member 375. In anembodiment, the retainer 360 includes a rim 362 that obstructs againstthe peripheral wall 387. The peripheral wall 387 constrains the movementof the retainer 360 beyond the front face 354 of the front panel 310. Aspring 364 for biasing the retainer 360 fits over the peripheral wall387 of the opening 386. Preferably, the spring 364 secures to theretainer 360 by engaging ridges 368, 368 on an interior surface 363 ofthe rim 362. The spring 364 is configured so that when the retainer 360is depressed inwards, the spring 364 biases the retainer 360 outward.

At the back panel 320, a release member 334 engages the tail portion 367of the first member 375. The release member 334 is moveable between afirst position where the first member 375 is in the extended position,and a second position in which the release member 334 moves the firstmember 375 into the contracted position. When the release member 334contacts the tail portion 367, the first member 375 is moved into acontracted position to bias the torsion spring 366 to return to itsoriginal position.

FIG. 4 shows the retainer 360 having a slit 460 which retains the firstmember 375 and second member 380 in a contracted and biased state. Theslit 460 is dimensioned to retain the first and second member 375 and380 when the first member 375 is in the contracted position. The slit460 is further dimensioned to obstruct a distal surface 410 of theretainer 360 against first and second members 375 and 380 when the firstmember 375 is in the extended position. In this way, the first member375 must be at least partially contracted in order for the slit 460 toretain the insertion coupling 250.

FIG. 5A is a cut-away view along lines A--A of FIG. 4 showing theinterior of the retainer 360 under an embodiment of the invention. FIG.5A shows the retainer 360 in an extended position distal to the frontface 262 of the accessory device 110. The slit 460 of the retainer 360is dimensioned to frictionally retain the first member 375 in acontracted and biased state within the confines of the retainer 360. Inan embodiment, the retainer 360 is dimensioned so that the first member375 exerts a force on an edge or surface (not shown) of the slit 420. Aslideable connection is formed at the base 385 by a slot 472 of thefirst member 375 coupling with a pair of protrusions 485 extending fromthe base 385. The first member 375 is then moveable in a lateraldirection shown by directional arrow 425. The first member 375 includesa hooked end 475. The tail portion 367 of the first member 375 extendsto couple with the release member 334 at the back face 352 of thehandheld computer 100.

FIG. 5B illustrates the first member 375 in an orientation forengagement with the back face 212 of the handheld computer 100. Thefirst member 375 is exposed when the distal surface 410 of the retainer360 is forced into the depressed position proximal to the front face 262of t he accessory device 110. In an embodiment, depressing the retainer360 overcomes the frictional retainment of the first member 375 withinthe slit 420. Once the retainer 360 is depressed, the first member 375is exposed and moves laterally in the direction of arrows 425 away fromthe second member 380, which is static with respect to the base 385. Thehooked end 475 of the first member 375 is then captured within thehandheld computer 100, thereby securing the handheld computer 100 to theaccessory device 110.

FIG. 6A shows a side view of a portion of the insertion coupling 250 inan "engaged" position, corresponding to the first member 375 beingengaged with the aperture 220 on the back face 212 of the handheldcomputer 100. In this position, the first member 375 is extended awayfrom the second member 380 (shown partially in phantom). The firstmember 375 is coupled to the base 385 (shown in FIG. 3) by slideablyengaging protrusions 485 of the base to the slot 472 of the first member375. The torsion spring 366 extends over the protrusions 485. In theengaged position, the first member 375 is extended from the secondmember 380, so that the bias applied by the torsion spring 366 isminimal or nonexistent. The torsion spring 366 exerts a lateral force onthe first member 375 when the first member is moved from the extendedposition (shown by FIG. 6A) to the contracted position (shown by FIG.6B).

FIG. 6B shows a side view of a portion of the insertion coupling 250 inan "disengaged" position, corresponding to the first member 375 beingcontained within the retainer 360 in a contracted state. In thisposition, the first member 375 is laterally aligned with the secondmember 380, so that the length of the first and second member 375 and380 combined is a minimum. The torsion spring 366 is biased to push thefirst member 375 laterally away from the second member 380. The biashelps to retain the first member 375 within the slit 420 of the retainer360. As further shown by FIGS. 6A and 6B, the tail portion 470 may beused to move the first member 375 further into the contracted state,thereby allowing release of the first member 375 from the aperture 220of the handheld computer 100.

Using Embodiments of this Invention

This invention allows the handheld computer 100 to be coupled with theaccessory device 110 in a swift and secure manner. Under an embodiment,the handheld computer 100 is slid along the front face of the accessorydevice 110 so that the connector of the accessory device establisheselectrical contact with the output or communications port of thehandheld computer 100. Features such as the alignment surfaces on thefront face 262 of the accessory device 110 and/or the back face 212 ofthe handheld computer 100 facilitate alignment of the electricalconnector with the port of the handheld computer 100. By electricallyconnecting the connectors, the aperture 220 of the handheld computer 100is aligned with the insertion coupling 250 of the accessory device 110.The handheld computer 100 may then be pushed back so that the insertioncoupling engages the aperture 220 to secure the handheld computer 100with the accessory device 110. The release member 334 on the front face262 of the accessory device 110 may be used to release the insertioncoupling from the handheld computer 100.

Embodiments of this invention enable the handheld computer 100 to besecured with the accessory device 110 using two swift motions consistingof sliding the handheld computer 100 along the front face 262 of theaccessory device 110 and then pushing the handheld computer 100 back toengage the insertion coupling 250. A user can hold the handheld computer100 and accessory device 110 in separate hands and move the handheldcomputer 100 or accessory device 110 in a manner that causes the twodevices to secure to one another by manipulating the alignment of thetwo devices while bringing the hands together. Therefore, in contrast toprevious devices, the user does not have to rotate the handheldcomputer, or to first let go of one of the devices to effectuate thecoupling that retains the two devices together.

The mechanical coupling also provides a tactile response that signalsthe handheld computer 100 is secured with the accessory device 110. Thetactile response may be in the form of a "snap", corresponding to thefirst spring-biased member expanding inside the back face of thehandheld computer 100. This simplifies coupling the handheld computer100 and accessory device 110, and further avoids mishaps that may ariseif the coupling between the handheld computer 100 and the accessorydevice 110 is unknowingly defective.

Conclusion

The foregoing description of various embodiments of the invention havebeen presented for purposes of illustration and description. It is notintended to limit the invention to the precise forms disclosed. Manymodifications and equivalent arrangements will be apparent.

What is claimed is:
 1. An accessory device for a handheld computer, thehandheld computer including a front face having a display, a back face,a pair of opposing lateral edges defining a width of the handheldcomputer, and a top edge and a bottom edge defining a length of thehandheld computer, wherein the accessory device comprises:a frontsurface and a back surface, a pair of opposing lateral sides and a topedge and a bottom edge, the pair of opposing lateral sides defining awidth of the accessory device, and the top edge and the bottom edgedefining a length of the accessory device; and a mechanical coupling forinserting into a back face of the handheld computer to detachably securethe front surface of the accessory device with the back face of thehandheld computer.
 2. The accessory of claim 1, further comprising aconnector separate from the mechanical coupling for providingcommunications between the accessory device and the handheld computer.3. The accessory device of claim 1, wherein the mechanical coupling isspring-biased to insert into the back face of the handheld computer. 4.The accessory device of claim 1, wherein the mechanical couplingcomprises:a base secured to the front face of the accessory device; anda first member extending from the base in a direction orthogonal to thefront face and being slideable in a direction parallel to the frontface, the first member being biased between an extended position and acontracted position, wherein the first member is adapted to be receivedin a slot of the back face of the handheld computer when in thecontracted position.
 5. The accessory device of claim 1, wherein thefirst member includes an enlarged endpiece that is adapted to obstructagainst an interior of the back face after the first member has beenexposed to release into the expanded state within the handheld computer.6. The accessory device of claim 1, wherein the electrical connector ispositioned on a bottom portion of the front surface to access an outputport of the handheld computer positioned at or near the bottom edge ofthe handheld computer.
 7. The accessory device of claim 1, wherein theaccessory device is dimensioned so that the width of the accessorydevice is less than the width of the handheld computer.
 8. The accessorydevice of claim 1, wherein the accessory device is dimensioned so thatthe width of the accessory device is within 90% of the width of thehandheld computer.
 9. The accessory device of claim 1, wherein theaccessory device is dimensioned so that at least two edges of theaccessory device are contained within a perimeter equal to thedimensions of the handheld computer.
 10. The portable computing assemblyof claim 1, wherein the accessory device is a modem device.
 11. Theportable computing assembly of claim 1, wherein the accessory device iseither a universal serial port device or a modem communication device.12. The accessory device of claim 4, wherein the mechanical couplingfurther comprises:a retainer engaged with an opening of the front faceof the accessory device, the retainer being moveable between an extendedposition distal to the front face of the accessory device and adepressed position proximal to the front face of the accessory device,the retainer being engaged with the first member to allow the firstmember to release into the extended state when the retainer is movedinto the depressed position.
 13. The accessory device of claim 4,wherein a distal surface of the retainer includes a slit that retainsthe first member in the contracted state, and wherein the retainer andthe first member are aligned so that upon the back face of the handheldcomputer depressing the retainer, the first member is engaged with anaperture on the back face of the handheld computer and then moved intothe expanded state to secure the first member with the handheldcomputer.
 14. The accessory device of claim 8, wherein the width of theaccessory device is 2.75 inches, and the width of the handheld computeris 3.0 inches.
 15. The accessory device of claim 8, wherein the bottomedge of the accessory device extends beyond a perimeter equal to thedimensions of the handheld computer.
 16. The accessory device of claim13, wherein the retainer is biased in the depressed position to move thedistal surface towards the extended position.
 17. The portable computingassembly of claim 15, wherein the accessory device includes a ledge thatsupports the bottom edge of the handheld computer.
 18. The accessorydevice of claim 16, wherein a release member couples to the first memberto move the first member between the contracted and expanded states. 19.The accessory device of claim 10, wherein the release member is anextension of the first member that is accessible from the back surfaceof the accessory device.
 20. A coupling for securing an accessory deviceto a handheld computer, the coupling comprising:a base secured to afront face of the accessory device; and a first member extending fromthe base in a direction orthogonal to the base and being slideable in adirection substantially parallel to the base, the first member beingbiased between an extended position and a contracted position, whereinthe first member is adapted to be received in a slot of a handheldcomputer when in the contracted position.
 21. The coupling of claim 20,further comprising:a retainer that retains the first member in thecontracted state, the retainer being engaged with an opening of a frontface of the accessory device, the retainer being moveable between anextended position distal to the front face and a depressed positionproximal to the front face, the retainer being engaged with the firstmember to allow the first member to release into the extended state whenthe retainer is moved into the depressed position.
 22. The coupling ofclaim 20, wherein the first member includes an enlarged endpiece thatobstructs against an interior of the handheld computer after the firstmember has been exposed to release into the expanded state within thehandheld computer.
 23. The coupling of claim 21, wherein a distalsurface of the retainer includes a slit that retains the first member inthe contracted state, and wherein the retainer and the first member arealigned so that upon the retainer being depressed, the first member isexposed from the retainer to move into the expanded state.
 24. Thecoupling of claim 23, wherein the retainer is biased in the depressedposition to move the distal surface towards the extended position. 25.The coupling of claim 24, wherein a release member of the accessorydevice couples to a tail portion of the first member to move the firstmember between the contracted and expanded states.
 26. An accessorydevice for a handheld computer, the handheld computer including a frontface having a display, a back face, a pair of opposing lateral edgesdefining a width of the handheld computer, and a top edge and a bottomedge defining a length of the handheld computer, wherein the accessorydevice comprises:a front surface and a back surface, a pair of opposinglateral sides and a top edge and a bottom edge, the pair of opposinglateral sides defining a width of the accessory device, and the top edgeand the bottom edge defining a length of the accessory device; a meansfor detachable securing the accessory device to the handheld computerusing a coupling that inserts into the back face of the handheldcomputer; and a means for providing communications between the accessorydevice and the handheld computer, the communications means beingseparate from the means for detachably securing the accessory devicewith the handheld computer.